Not a runner.
Slide was too late to factor in. Defenseless essentially means not a qb looking to pass or a receiver in the process of catching. As long as they aren’t defenseless, all you can’t do is make first contact with the crown of your helmet. If they are defenseless, then you can’t hit them with anything in their head/neck area (plus an indicator of targeting). So if the runner had been defenseless, that an easy targeting call. But he wasn’t, and replay verified he led with the shoulder, so it doesn’t matter where he hit the runner…thus no targeting.